首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   4177篇
  免费   239篇
  国内免费   33篇
耳鼻咽喉   56篇
儿科学   48篇
妇产科学   12篇
基础医学   449篇
口腔科学   152篇
临床医学   319篇
内科学   1109篇
皮肤病学   80篇
神经病学   317篇
特种医学   119篇
外科学   824篇
综合类   17篇
预防医学   82篇
眼科学   50篇
药学   425篇
中国医学   6篇
肿瘤学   384篇
  2023年   17篇
  2022年   79篇
  2021年   117篇
  2020年   65篇
  2019年   90篇
  2018年   103篇
  2017年   77篇
  2016年   88篇
  2015年   87篇
  2014年   140篇
  2013年   183篇
  2012年   269篇
  2011年   279篇
  2010年   156篇
  2009年   128篇
  2008年   243篇
  2007年   254篇
  2006年   217篇
  2005年   233篇
  2004年   214篇
  2003年   203篇
  2002年   179篇
  2001年   77篇
  2000年   92篇
  1999年   72篇
  1998年   62篇
  1997年   43篇
  1996年   29篇
  1995年   30篇
  1994年   22篇
  1993年   16篇
  1992年   53篇
  1991年   48篇
  1990年   54篇
  1989年   49篇
  1988年   52篇
  1987年   54篇
  1986年   40篇
  1985年   52篇
  1984年   18篇
  1983年   18篇
  1981年   12篇
  1980年   15篇
  1979年   14篇
  1978年   9篇
  1976年   13篇
  1975年   13篇
  1974年   10篇
  1972年   8篇
  1967年   10篇
排序方式: 共有4449条查询结果,搜索用时 15 毫秒
101.
A 52-year-old man without a history of asthma or allergic diseases died of ventricular fibrillation early in the morning. His autopsy revealed no significant findings, except for a mild mural-thickening localized at the proximal region of the right coronary artery. Microscopic examination showed periarteritis with infiltration of numerous eosinophils in the adventitia. No significant vasculitis was found in any other organs. Based on the findings this seems to be the second reported case of isolated eosinophilic coronary periarteritis.  相似文献   
102.
103.

Background

The functional SYNTAX score (FSS) has been shown to improve the discrimination for major adverse cardiac events compared with the anatomic SYNTAX score (SS) while reducing interobserver variability. However, evidence supporting the noninvasive FSS in patients with multivessel coronary artery disease (CAD) is scarce.

Objectives

The purpose of this study was to assess the feasibility of and validate the noninvasive FSS derived from coronary computed tomography angiography (CTA) with fractional flow reserve (FFRCT) in patients with 3-vessel CAD.

Methods

The CTA-SS was calculated in patients with 3-vessel CAD included in the SYNTAX II (SYNergy between percutaneous coronary intervention with TAXus and cardiac surgery II) study. The noninvasive FSS was determined by including only ischemia-producing lesions (FFRCT ≤0.80). SS derived from different imaging modalities were compared using the Bland-Altman and Passing-Bablok method, and the agreement on the SS tertiles was investigated with Cohen’s Kappa. The risk reclassification was compared between the noninvasive and invasive physiological assessment, and the diagnostic accuracy of FFRCT was assessed by the area under the receiver-operating characteristic curve using instantaneous wave-free ratio as a reference.

Results

The CTA-SS was feasible in 86% of patients (66 of 77), whereas the noninvasive FSS was feasible in 80% (53 of 66). The anatomic SS was overestimated by CTA compared with conventional angiography (27.6 ± 6.4 vs. 25.3 ± 6.9; p < 0.0001) whereas the calculation of the FSS yielded similar results between the noninvasive and invasive imaging modalities (21.6 ± 7.8 vs. 21.2 ± 8.8; p = 0.589). The noninvasive FSS reclassified 30% of patients from the high- and intermediate-SS tertiles to the low-risk tertile, whereas invasive FSS reclassified 23% of patients from the high- and intermediate-SS tertiles to the low-risk tertile. The agreement on the classic SS tertiles based on Kappa statistics was slight for the anatomic SS (Kappa = 0.19) and fair for the FSS (Kappa = 0.32). The diagnostic accuracy of FFRCT to detect functional significant stenosis based on an instantaneous wave-free ratio ≤0.89 revealed an area under the receiver-operating characteristics curve of 0.85 (95% CI: 0.79 to 0.90) with a sensitivity of 95% (95% CI: 89% to 98%), specificity of 61% (95% CI: 48% to 73%), positive predictive value of 81% (95% CI: 76% to 86%), and negative predictive value of 87% (95% CI: 74% to 94%).

Conclusions

Calculation of the noninvasive FSS is feasible and yielded similar results to those obtained with invasive pressure-wire assessment. The agreement on the SYNTAX score tertile classification improved with the inclusion of the functional component from slight to fair agreement. FFRCT has good accuracy in detecting functionally significant lesions in patients with 3-vessel CAD. (A Trial to Evaluate a New Strategy in the Functional Assessment of 3-Vessel Disease Using SYNTAX II Score in Patients Treated With PCI; NCT02015832)  相似文献   
104.
105.
The effects of dietary polyphenols on human health have mainly been discussed in the context of preventing degenerative diseases, particularly cardiovascular diseases and cancer. The antioxidant properties of polyphenols have been widely studied, but it has become clear that the mechanism of action of polyphenols extends beyond the modulation of oxidative stress, as they are poorly absorbed from the digestive tract. The purpose of this study was to clarify the effects of polyphenols on the colonic environment, intestinal barrier function, and gut microbiota. We demonstrated that dietary polyphenols derived from aronia, haskap, and bilberry, markedly elevated the amount of fecal mucin and immunoglobulin A (IgA) as an intestinal barrier function and ameliorated the disturbance in gut microbiota caused by a high fat diet in rats. These results suggest that dietary polyphenols play a significant role in the prevention of degenerative diseases through improvement of the colonic environment without any absorption from the digestive tract.  相似文献   
106.
Recent studies suggest a relationship between intestinal microbiota and metabolic syndromes; however, the underlying mechanism remains unclear. To clarify this issue, we assessed the effects of bacterial cell wall components on adiponectin, leptin and resistin secretion from rat visceral adipocytes in vitro. We also measured the relative population of Firmicutes and Bacteroidetes in fecal microbiota and the amount of fecal mucin as an intestinal barrier function, when mice were fed a high-fat diet. In the present study, we demonstrated that bacterial cell wall components affect the secretion of adipokines, depending on the presence of antigens from gram-positive or gram-negative bacteria. Lipopolysaccharide markedly inhibited adiponectin, leptin, and resistin secretion, whereas peptidoglycan increased adiponectin secretion and decreased resistin secretion in vitro. In vivo experiments showed that the high-fat diet increased the population of Firmicutes and decreased that of Bacteroidetes. In contrast, the high-fat diet downregulated the stool output and fecal mucin content. These results demonstrate that bacterial cell wall components affect the onset of metabolic syndromes by mediating the secretion of adipokines from visceral adipose tissue. Furthermore, we believe that metabolic endotoxemia is not due to the increasing dominance of gram-negative bacteria, Bacteroidetes, but due to the depression of intestinal barrier function.  相似文献   
107.
108.
109.
Coagulopathy is still a frequent complication in the surgical treatment of acute aortic dissection. This study was designed to clarify the influence of acute aortic dissection on the clotting-fibrinolysis system and platelet function. From January 1993 to December 1994 21 patients with proven Stanford type B aortic dissection underwent a series of tests and procedures at our institution. There were 6 women and 15 men, aged 37–74 years (mean 62 years). All patients were admitted within 14 days of onset of dissection. No patient had complications requiring surgery and none died during the observation period. We observed a severe inflammatory reaction with activation of the clotting-fibrinolysis system immediately after onset of dissection. The platelet maximum aggregation rates were also decreased transiently after onset of the dissection. D-dimer values remained elevated throughout, the observation period. A rational approach to the surgical treatment of acute aortic dissection should involve coping with its activated clotting-fibrinolysis system and platelet dysfunction in addition to tissue friability.  相似文献   
110.
Tumor necrosis factor-alpha (TNF-alpha) is considered to be 1 of the factors that induce vasculitis, including coronary artery aneurysm (CA), in Kawasaki disease (KD), because the blood concentration of TNF-alpha is higher in patients with CA compared with those without. Therefore, an anti-TNF-alphaagent (infliximab) was administered to a 1-month-old girl with refractory KD complicated by CA and subsequently, the CA improved and KD was controlled without complications 20 months after the onset.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号